By forcing Al Qaeda's leadership to flee into hiding, the US and its allies have clearly hobbled the group's ability to coordinate major terrorist attacks.

While the capture or killing of Osama bin Laden and his top lieutenants remains the ultimate US goal, the mere splintering and scattering of the organization's leadership is likely to disrupt communication and any plotting the group could carry out soon.

Yet Al Qaeda's independent cell structure, as well as its global roots, means the threat of further attacks on the West remains a distinct possibility, with or without its inspirational or military leaders.

Al Qaeda's self-reliant cliques, for instance, can still raise money through credit-card fraud and other scams. At the same time, the US's routing of the last Al Qaeda redoubt in Afghanistan, in the moonscape of Tora Bora, may spark new resolve among young followers in other countries.

"The supply of people willing to go to their Maker in suicide-style attacks is still large," says Gregory Treverton, an analyst at the Rand Corp. in Santa Monica, Calif. "But the managerial and organizational talent - and personal charisma - that bin Laden brought has clearly been diminished."

So far, the American effort to capture or kill bin Laden and his inner circle has yielded mixed results. Conflicting reports swirl daily about their location. But Pentagon officials don't rule out that bin Laden himself has escaped into Pakistan.

As of early Monday, the US had taken five prisoners from the Afghan war into custody, including one American and one Australian who had been fighting with the Taliban.

Defense Secretary Donald Rumsfeld also reported another 30 or 31 Al Qaeda fighters were being held by local Afghan commanders. Local reports indicated that two of the captives were senior Al Qaeda members. The others hadn't been identified, so it was unclear whether they were foot soldiers or leaders. As for Mr. bin Laden himself, Mr. Rumsfeld said, in what is becoming a common refrain: "There is a question mark as to his exact location."

Whatever his whereabouts, the big picture is clear: Al Qaeda's command-and-control structure has been severely impacted.

Even so, a huge rank-and-file membership remains: Some 25,000 to 30,000 recruits have passed through Al Qaeda's training camps over the years. Many of them have formed into individual units - including so-called "sleeper cells" - operating in scores of countries.

"In the short term, killing or capturing bin Laden will increase the threat of new attacks," says L. Paul Bremer, former US ambassador for counterterrorism. "Cells may want to take action, especially if we capture him."

They can still raise funds on their own. And many don't need nearly as much money as the relatively large groups that carried out the Sept. 11 attacks. The groups also don't need bin Laden to carry on the ideology of their cause.

But over time, the top-tier cells may atrophy. Indeed, some observers see a four-tier system within Al Qaeda. The elite groups - such as those that carried out the Sept. 11 attacks - were closely tied to the senior leadership.

"They typically did their reconnaissance and planning and then went back to the center to get approval and funding," says Magnus Ranstorp of the Centre for the Study of Terrorism and Political Violence in St. Andrews, Scotland.

The lower tiers are less potent, but also less dependent on the senior leadership. That means they're more likely to survive bin Laden's capture or demise.

Second-level groups are typically given money and told to go out and cause damage, but with less support or direction than top-tier groups. Ahmed Rassam, arrested in 1999 for allegedly plotting to bomb the Los Angeles airport, is an example.

Third-tier groups are typically well established in other countries, such as the Philippines. Al Qaeda gives them "venture capital" style funding. But they typically have other sources of support and may continue virtually unabated.

Fourth-tier members have typically gone through training camps but haven't become active since. They are ripe for recruitment by any successor organizations.

Without the top leadership, though, Al Qaeda may not be as potent over the long term.

"If we can decapitate them - by taking out the top intellectual and charismatic leadership - over time their capacity to operate will degenerate," says Mr. Bremer. The Abu Nidal Organization, for instance, was the world's most-feared terrorist group in the 1980s. It's now essentially defunct, in part because its leader, Abu Nidal, is ailing and inactive.

Still, the conditions that led to Al Qaeda's success - everything from poverty to religious fundamentalism to easy access to global travel - remain.

For that reason, observers say, there's a danger in capturing or killing bin Laden: that the public, assuming the threat has dissipated, will soften its support for the global war on terrorism.

"The authorities have a real public-relations job to do," says Dr. Ranstorp. They'll need to shore up public will to continue unearthing people who've gone through Al Qaeda camps, dealing with breeding-ground states like Somalia, and more. "It's a mammoth task," he says.